All of the pics are Rios. I have killed many Rios with darker than usual fans. It's not that uncommon, especially in south Texas. Most of the Rios I have killed in north Texas however have had the usual light colored fans, but I have killed darker ones there too. Look at the secondary feathers on the fans. They are totally different from an Eastern.
Exactly...I've seen some Rios with very dark tail feathers and most that I've seen are usually in south Texas. I've seen some Rio's up in north TX on the grasslands that were trimmed in almost white like a Merriam's. And I have a Merriam's fan that's trimmed in buff more like a Rio. I've also seem Easterns with lighter trimmed tail feathers. As mentioned above there are some birds have different color variations than most of the general population.
I had a couple of dark fans like that that I've dismantled to use the feathers, but I have one that is still slightly darker than the rest. In this photo the fans on the left and right are rios and the top fan over them is an eastern. Notice the eastern is more chestnut reddish brown. I harvested an eastern this year with a fan somewhat darker than this but it still had a lot of reddish coloring in it...